Supporting arm

Abstract

A supporting arm consists of telescoping sections (1-4, 17-19) which are mutually supported by roller bearings such as needle bearings (8) or ball bearings (25). The cross sectional shape of the sections (1-4, 17-19) is polygonal, so as to provide a high bending and torsional stiffness. By providing grooves in the supporting faces (10, 23, 24) of the sections, the strength characteristics as well as the behavior during telescoping under high loads may be enhanced.

I claim: 
     
       1. Supporting arm provided with telescoping members which cooperate by means of roller bearings for supporting a load in an essentially horizontally displaceable manner, wherein the telescoping members consist of sections with a closed polygonal cross section, and all roller bearing races are internal or external section faces with a generally planar surface. 
     
     
       2. Supporting arm according to claim 1, wherein more than two telescoping members are provided, whereby both external as well as internal section faces of any telescoping member other than the outermost and the innermost telescoping member are roller bearing races. 
     
     
       3. Supporting arm according to claim 1, wherein the section faces forming roller bearing races are provided with longitudinal bearing grooves which are formed to receive the bearings, such that the bearings are not displaceable transverse to the supporting arm. 
     
     
       4. Supporting arm according to claim 1, wherein the bearings are needle bearings and the sections consist of walls which in circumferential direction run at an angle in the same direction with respect to each other. 
     
     
       5. Supporting arm according to claim 3, wherein the bearings are ball bearings, and the section faces forming roller bearing races are provided with grooves which in cross section are partly circular. 
     
     
       6. Supporting arm according to claim 5, wherein in each section face forming a roller bearing race at least two parallel grooves are provided, such that the pairs of such section faces enclose at least two parallel series of balls. 
     
     
       7. Supporting arm according to claim 1, wherein each section has internally and/or externally three section faces forming roller bearing races. 
     
     
       8. Supporting arm according to claim 1, wherein each section internally and/or externally has four section faces forming roller bearing races. 
     
     
       9. Supporting arm according to claim 1, wherein the sections have an octagonal cross section, and in circumferential direction consist of alternately walls with and walls without a section face forming roller bearing races, whereby opposing walls without such section face are parallel to each other in pairs. 
     
     
       10. Supporting arm according to claim 9, wherein the opposite pairs of walls with a section face forming a roller bearing race are parallel to each other. 
     
     
       11. Supporting arm according to claim 9, wherein one pair of walls without section faces forming a roller bearing race is disposed horizontally and one pair is disposed vertically. 
     
     
       12. Supporting arm according to claim 10, wherein the section with the smallest cross sectional surface in circumferential direction consists of alternately two walls with and one wall without section faces forming a roller bearing race, and the pair of opposing walls without such section face extends vertically. 
     
     
       13. Supporting arm according to claim 11, wherein the section with the smallest cross sectional surface in circumferential direction consists of alternately two walls with and one wall without section faces forming a roller bearing race, and the pair of opposing walls without such section face extends vertically. 
     
     
       14. Supporting arm according to claim 1, wherein the outermost section is externally provided with a longitudinal groove with undercut cross section for receiving a T-shaped fixing member. 
     
     
       15. Supporting arm according to claim 1, provided with more than two sections, wherein the section with the smallest cross sectional surface is lockable with respect to the next surrounding section when completely collapsed therein.